During the processing of waste, for instance sewage sludge, manure etc, the waste is concentrated into piles for storage and for transportation. When waste of this sort is concentrated into piles, it is often desirable to cover the waste piles to minimize the emission of odor. Additionally, as recycling has become more common across the United States, diluents to the organic waste stream have been diverted, and the waste stream for landfills has become more concentrated with putrid and putrifiable materials and therefore more offensive. As a result, a need has developed for a cover that resists odor permeation for time periods on the order of 24 hours or more. Such a cover would also be useful, for example, for covering all sorts of organic waste—such as sewage sludge, animal waste, food waste and municipal waste—in a truck during transport, as all of these utilities require odor suppression for periods of several hours.
Spray-on coatings have been developed to provide an effective cover to landfill and waste piles. These are primarily intended to physically stabilise the waste (e.g. prevent blowing litter, block access by disease vectors and act as a fire retardant) and only incidentally may suppress odors. They include the coatings described in U.S. Pat. Nos. 5,161,915; 5,275,508; 5,385,429; 5,525,009; and 7,544,243 (the disclosures of which are incorporated by reference here in their entirety), which are marketed under the registered trademark POSI-SHELL by LSC Environmental Products, LLC of Apalachin, N.Y. These cover materials typically comprise a mixture of water, mineral binder (such as cement kiln dust, “CKD,” or similar materials), and fibers (both cellulose and synthetic) that can be sprayed onto a waste pile and allowed to set to provide a cover that is effective to stabilise the waste. Other known cover materials, for example, those described in U.S. Pat. Nos. 5,082,500 and 5,516,830, are primarily fiber based. Such prior cover materials typically stabilize the waste, but the gaseous components of the waste quickly permeate the cover and escape, so that odors are not effectively suppressed when the waste is itself offensively odiferous.
One technique described in the art for addressing the odor problem is to spray an aqueous aerosol of essential oil and nonyl phenoxy polyethoxy ethanol into the air above the source of the odor. While this is said to be effective, it requires sophisticated equipment and expertise to generate a continuous aerosol, and there is little residual effect—within a short period after the application is terminated, the odor returns. In another approach the odor-suppressant is specifically designed for mixing into the odor generating material. This approach suffers from the drawback that that the odor-suppressing composition must come into intimate contact with the odor-generating material throughout its entire mass.
Aspects of the present invention overcome these and other limitations of the prior art and provide an effective odor-barrier bulk material pile cover that can be easily applied and maintained and that provides more effective odor suppression over longer times.